1. Field of the Invention
The present invention relates to a balancer device of an in-line engine, and more particularly to a balancer device in which a balance shaft is assembled in a cylinder block of the engine.
2. Description of the Prior Art
It is well known that a balancer device has been used for an in-line engine in order to suppress the vibration due to the reciprocating movements in the engine. Such a balancer device is disclosed, for example, in Japanese Patent Provisional Publication No. 63-167145, in which the balancer device is equipped in an in-line four cylinder engine. First and second balance shafts are arranged to be generally parallel with a crankshaft of the engine and to be opposite to each other relative to the crankshaft. The first and second balance shafts are rotated at twice the rotating speed of the crankshaft but rotating reversely with each other. The first balance shaft is rotated in the same direction as the crankshaft is rotated, and the second balance shaft is rotated in the reverse direction of the rotating direction of the crankshaft. Each balance shaft includes a first journal disposed near the front portion of the engine and a second journal disposed near the middle portion of the engine. A pair of unbalance portions are disposed at both sides of the second journal, respectively. The first and second journals are supported to first and second bearings formed to the cylinder block, respectively. The balance shaft is equipped to the cylinder block by being inserted in the direction of the crankshaft axis from the front side of the cylinder block. The balance shaft is shaped such that the diameter of the first journal is larger than that of the second journal and the diameter of the second journal is larger than twice the radius of the unbalance portions.
However, it is preferable that the diameter of the first journal is smaller than that of the second journal since the second journal receives a load greater than the first journal does.